1. Field of the Invention
The present invention relates to a polymaneuverable canopy and to the process of controlling a canopy of this type for individual parachute equipment intended either for saving passengers or crew from an aircraft in difficulty, or for the landing of parachutists of airborne forces.
2. Description of the Prior Art
Three large families of personnel canopies are known at the present time, which are intended for the abovementioned uses and which hitherto have been canopies of a generally hemispherical shape:
so-called solid, non-maneuverable canopies, that is to say canopies generally not equipped with apertures for the escape of air through the dome, and which descend practically vertically through the atmosphere. The majority of canopies in use are still of this type. They have the disadvantage of the lack of maneuverability.
Steerable canopies: these canopies comprise domes in which suitable cutouts or openings are provided, more particularly on their rear faces, or else air escape nozzles, so arranged that the resulting flow or lift dissymmetrical to the aerodynamic plane will generate a resultant force directed towards the front of the ca thus causing the latter to move in that direction. It is customary to say that these canopies have a forward drive. This type of canopy is known in particular from French Pat. No. 1,550,628, British Pat. No. 1,037,928, and U.S. Pat. No. 3,343,769. Their steerability is achieved with the aid of two maneuver controls, left and right, connected symmetrically to the rear part of their dome, for the purpose of turning the canopy to the right and left respectively when the parachutist pulls down the right-hand and left-hand controls respectively, and of braking the forward movement of the canopy when the parachutist operates both controls symmetrically.
Although these canopies have the advantage of being steerable, nevertheless they have numerous operational disadvantages.
For these canopies, the permanence of their forward drive is incompatible with high density mass jumps because of the considerable increase in the frequency of collisions during descent, particularly in the first few moments after the opening of the canopies of parachutists who have just jumped, for example, from the two side doors of the carrier aircraft. Since the canopies open in directions which are distributed in random fashion, it frequently occurs in fact that two canopies will open in such a manner that their directions of advance will be opposite to one another and that consequently the parachutists will collide without having time to react.
Moreover, in jumps from very low altitudes the parachutist does not always have time to change the direction of his horizontal movement by turning so as to make his landing in a position favoring safety, because as a rule it is attempted to land facing the wind. In cases where the parachutist has not succeeded in turning his parachute to face the wind by making a suitable turn, his resultant ground-speed of advance may be high, because it may be the sum of the parachute's forward drive and the velocity of the wind.
Finally, this type of parachute used as a rescue parachute may be the cause of landing mishaps. The user, who is usually not trained in parachute jumping disciplines, and who in addition is often subject to psychological traumatism caused by his bailing out, is in fact not always able, or does not always have the automatic reflex required, to take advantage of the steerability of the canopy in order to ensure his safe landing, if necessary by avoiding certain obstacles on the ground, such as trees for example, and by assuming a position facing the wind.
Finally, although these parachutes very often make it possible for the relative speed of impact with the ground to be reduced on landing by an amount equal to the speed of the parachute itself, on the other hand they have the disadvantage that, when the velocity of the wind is greater than the parachute's forward drive contact is made with the ground in the opposite direction to the forward drive.
Finally, a last type of canopy comprises canopies having directional maneuverability. These more recent canopies are those disclosed in the patents filed in France under No. 75/19,553 now French Pat. No. 2,315,435 and No. 76/07,252 now French Pat. No. 2,343,650, by the firm AERAZUR.
These canopies have the advantage of not having a forward drive, so that they considerably increase the safety of mass jumps of airborne forces, and of not having a speed of impact with the ground higher than the wind speed. In addition, these canopies permit a certain lateral or axial maneuverability because, generally by pulling two maneuver controls, it is possible to reduce the speed of horizontal displacement due to the relative wind and to land at a lower resultant speed of advance.
However, these canopies still have two disadvantages due to the lack of rotational maneuverability. The parachutist is in fact often directed in a direction which does not always enable him to see any obstacles on the ground in his direction of movement, and with these canopies he is not able to make a turn in order to face the obstacles. Finally, because of his horizontal movement in a random direction, the landing may be made in any direction in relation to that of the resultant speed of movement.